1. Field of the Invention
This disclosure relates to a semiconductor device provided with a circuit including a semiconductor element such as a transistor, and a method for driving the semiconductor device.
2. Description of the Related Art
A memory cell which can retain data by using an oxide semiconductor transistor without performing refresh operation for a long time is proposed. In such a memory cell, an adequate time is required until next refresh operation is performed; therefore, unlike a conventional DRAM using a silicon transistor, it does not mean that the memory cell simply requires regular-interval refresh operation. Patent Documents 1 to 3 disclose techniques with consideration of such peculiarity.